Alloy



ai 1932. N. B. PlLLlNG 1,858,415

ALLOY Filed Sept 25, 1924 NITNESSES- INVENTOR 4 Murray 5. p/l/ligg ATTORNEY- Patented May 17, 1932 UNITED STATES PATENT oFFlcE mm is. BILLING, or. rtamrrnnn, NEW JERSEY, ASSIGNOB 'ro wnsrmonousn ELECTRIC a moracruamu comramr, a coarom'rron or nmsnvama Annoy Application filed September 28, 1924 Serial No. 739,260.

My invention relates to alloys, more particularly to materials adapted for use in electrical instruments. a

It is desirable in many cases to provide a resistor material for use in electrical instruments that has a negative temperature coeflicient of resistance in order to compensate for the positive temperature coeflicient of a part of the instrument. To accomplish this result there has been proposed an alloy of nickel and copper, which has a negative temperature coeflicient and is known as negatan. This material, which consists of 50% nickel and the remainder copper, with sometimes the addition of very small amounts of magnesium, has a relatlvely low negative temperature coefiicient of resistance, usually about .00012, per degree centigrade but varying somewhat according .to the conditions of manufacture. Furthermore, this material has a high thermo-electric power against co per.

t is among the objects of my invention to provide an allo having a high negative temperature coeflicient of resistance and having a low thermo electric power against copper.

In practicing my invention, I have studied substantially the entire series of alloys, including copper, nickel and manganese as the rincipal constituents thereof, and have ound that there is a region extending over a considerable ran e of amounts of the alloying ingredients in which the temperature coeflicient is negative and is relatively high much higher than that of negatan. I have further found that the alloys having the highest negative coeflicients have relatively high resistivities, which is of great advantage in materials for compensation purposes in electrical instruments.

'The accompanying drawin is a diagram showing'the temperature coe cients of various alloys that I have studied and indicating the regions of equal coefficients. The fig ures denoting each of the regions should be multiplied 10 to obtain the correct value of the temperature coefficient.

Referring to the figure, it will be found that i the addition of nickel to copper rapidly lowers the coeflicient until at 33% nickel content, it is zero; the addition of copper' to nickel likewise reduces the coeflicient to zero at 58% nickel content; the intermediate alloys have negative coefficients, with a minimum at about nickel (negatan).

The addition of manganese up to 10% to i When manganese is added to copper, the

coeflicient is very rapidly decreased, reaching nearly zero at about 10% manganese,

resistance curve of copper manganese alloys in this range is not linear, but asses through a maximum, so that a given a loy may have a positive, or negative coeflicient depending on the temperature interval through which it is measured. The map of this region cannot therefore be very closely defined. Manganin is an alloy of this type in which a Zero coefiicient is had by modifying the maximum on the curve so that it occurs at room temperature.

The first 10% of nickel added to coppermanga-nese alloys is without appreciable ef feet on the coefficient.

Manganese added to nickel reduces the co-' efficient at first relatively slowly, but pass- ,ing through a minimum in the negative cohaving been made. In the interior of the 100 passing through a flat minimum and rising 1 again at 30% manganese. The temperaturealong the copper nickel base.

diagram, the coeflicients first sink to zero and then below a great field of negative vcoeflicient alloys occurs, forming at least half the area of the diagram. There are two negative fields-that have been discovered. The first is that peculiar to thepure nickel-coppers, rapidly eliminated by an addition of manganese, and hence forming a narrow zone Second, the great interior field, which connects with the nickel-manganese base line; its limits in the direction of the manganese corner have not been traced. The maximum negative coefficient is not found at equi-atomic proportions of copper, nickel and manganese but at 10% removed from that condition. This alloy has a composition of about:

Per cent Copper 24 Nickel 36 Manganese 40 with a temperature coefiicient of -.00O32 per 1 C.

The term manganese refers to the product known as pure manganese, which at the I present stage of the metallurgical art, contains about 95% of manganese.

ments present include about 1.7% iron and 1.5% silicon. It is apparent that all my alloys contain the latter elements in amounts proportional to the nominal content 'of manganese, andsuch proportional impurities will be understood herein in all instances where the content of manganese is specified.

It will be noted that I have produced an entirely new series of alloys having high negative temperature coeflicients of resistance and a low thermo-electric power against copper which alloys are workable at room temperature and are malleable at elevated temperatures. The negative temperature coefliclents of resistance of my new alloys are as high as four times that of. negatan and the most malleable of such alloys has'twice the temperature coeflicient thereof. My alloys have a high resistivity compared to negatan and are, therefore, much more suitable for use in electrical instruments than the said material.

In my copending application, Serial No. 736,827 filed Sept. 10,1924, for alloys, I have described and claimed alloys of the same three metals but having zero temperature coefiicients, high resistivities and low thermoelectric power against copper.

I claim as my invention:

1. An alloy comprising 15% to 55% copper, less than 47% and more than 22% nickel and more than 20% manganese, said alloy having a negative temperature coeflicient of resistance greater than 1X10" per degree centigrade.

2. An alloy comprising 5% to 49% copper, more than 22% and less than 45% nickel and more than 20% manganese, said alloy having Other elea negative temperature coefiicient of resistance greater than 1.5X10" per degree centigrade.

3. An alloy comprising 5% to 45% copper, i

perature coefficient of resistance greater than 3X 10" per degree centigrade.

- 6. An alloy comprising approximately 24% copper, 36% nickel and 40% manganese.

In testimony whereof, I have hereunto subscribed my name this second day of September 1924.

NORMAN B. PILLING. 

